MULTIDRUG RESISTANCE IN WILD BIRD POPULATIONS: IMPORTANCE OF THE FOOD CHAIN

Antimicrobial resistance among clinically significant bacteria in wildlife: An overlooked one health concern

Antimicrobial resistance (AMR) has emerged as a critical global health challenge. However, the significance of AMR is not limited to humans and domestic animals but extends to wildlife and the environment. Based on the analysis of > 200 peer-reviewed papers, this review provides comprehensive and current insights into the detection of clinically significant antimicrobial resistant bacteria and resistance genes in wild mammals, birds and reptiles worldwide. The review also examines the overlooked roles of wildlife in AMR emergence and transmission. In wildlife, AMR is potentially driven by anthropogenic activity, agricultural and environmental factors, and natural evolution. This review highlights the significance of AMR surveillance in wildlife, identifies species and geographical foci and gaps, and demonstrates the value of multifaceted One Health strategies if further escalation of AMR globally is to be curtailed.

First Insights on Resistance and Virulence Potential of Escherichia coli from Captive Birds of Prey in Portugal

Captive birds of prey are often used for pest control in urban areas, while also participating in falconry exhibitions. Traveling across the country, these birds may represent a public health concern as they can host pathogenic and zoonotic agents and share the same environment as humans and synanthropic species. In this work, Escherichia coli from the cloacal samples of 27 captive birds of prey were characterized to determine their pathogenic potential. Isolates were clustered through ERIC-PCR fingerprinting, and the phylogenetic groups were assessed using a quadruplex PCR method. Their virulence and resistance profile against nine antibiotics were determined, as well as the isolates' ability to produce extended-spectrum β-lactamases (ESBLs). The 84 original isolates were grouped into 33 clonal types, and it was observed that more than half of the studied isolates belonged to groups D and B2. Most isolates presented gelatinase activity (88%), almost half were able to produce biofilm (45%), and some were able to produce α-hemolysin (18%). The isolates presented high resistance rates towards piperacillin (42%), tetracycline (33%), and doxycycline (30%), and 6% of the isolates were able to produce ESBLs. The results confirm the importance of these birds as reservoirs of virulence and resistance determinants that can be disseminated between wildlife and humans, stressing the need for more studies focusing on these animals.

Impacts of coprophagic foraging behaviour on the avian gut microbiome

Avian gut microbial communities are complex and play a fundamental role in regulating biological functions within an individual. Although it is well established that diet can influence the structure and composition of the gut microbiota, foraging behaviour may also play a critical, yet unexplored role in shaping the composition, dynamics, and adaptive potential of avian gut microbiota. In this review, we examine the potential influence of coprophagic foraging behaviour on the establishment and adaptability of wild avian gut microbiomes. Coprophagy involves the ingestion of faeces, sourced from either self (autocoprophagy), conspecific animals (allocoprophagy), or heterospecific animals. Much like faecal transplant therapy, coprophagy may (i) support the establishment of the gut microbiota of young precocial species, (ii) directly and indirectly provide nutritional and energetic requirements, and (iii) represent a mechanism by which birds can rapidly adapt the microbiota to changing environments and diets. However, in certain contexts, coprophagy may also pose risks to wild birds, and their microbiomes, through increased exposure to chemical pollutants, pathogenic microbes, and antibiotic-resistant microbes, with deleterious effects on host health and performance. Given the potentially far-reaching consequences of coprophagy for avian microbiomes, and the dearth of literature directly investigating these links, we have developed a predictive framework for directing future research to understand better when and why wild birds engage in distinct types of coprophagy, and the consequences of this foraging behaviour. There is a need for comprehensive investigation into the influence of coprophagy on avian gut microbiotas and its effects on host health and performance throughout ontogeny and across a range of environmental perturbations. Future behavioural studies combined with metagenomic approaches are needed to provide insights into the function of this poorly understood behaviour.

Gulls in Porto Coastline as Reservoirs for Salmonella spp.: Findings from 2008 and 2023

Gulls act as intermediaries in the exchange of microorganisms between the environment and human settlements, including Salmonella spp. This study assessed the antimicrobial resistance and molecular profiles of Salmonella spp. isolates obtained from fecal samples of gulls in the city of Porto, Portugal, in 2008 and 2023 and from water samples in 2023. Antimicrobial susceptibility profiling revealed an improvement in the prevalence (71% to 17%) and antimicrobial resistance between the two collection dates. Two isolate collections from both 2008 and 2023 underwent serotyping and whole-genome sequencing, revealing genotypic changes, including an increased frequency in the monophasic variant of S. Typhimurium. qacE was identified in 2008 and 2023 in both water and fecal samples, with most isolates exhibiting an MDR profile. The most frequently observed plasmid types were IncF in 2008 (23%), while IncQ1 predominated in 2023 (43%). Findings suggest that Salmonella spp. circulate between humans, animals, and the environment. However, the genetic heterogeneity among the isolates from the gulls' feces and the surface water may indicate a complex ecological and evolutionary dynamic shaped by changing conditions. The observed improvements are likely due to measures to reduce biological contamination and antimicrobial resistance. Nevertheless, additional strategies must be implemented to reduce the public health risk modeled by the dissemination of pathogens by gulls.

Airsacculitis Caused by Enterobacteria and Occurrence of Eggs of the Superfamily Diplotriaenoidea in Feces of Tropical Screech Owl (Megascops choliba) in the Amazon Biome

This study aims to report the clinical signs, therapeutic strategy, necropsy results, and histopathological findings of airsacculitis caused by enterobacteria and the occurrence of eggs from the superfamily Diplotriaenoidea in the feces of Megascops choliba in the Amazon biome. A tropical screech owl nestling was rescued and admitted for hand-rearing. The animal was kept hospitalized for five months. It was fed a diet based on Zophobas morio larvae and thawed chicken breast meat with vitamin and mineral supplements. On the 37th day of hacking training for release, the owl showed weakness, lack of appetite, regurgitation, cachexia, dyspnea, ruffled feathers, dry droppings in the vent and pericloaca, and diarrhea. The parasitological examination showed eggs of the Diplotriaenoidea superfamily in the feces. The therapy employed included oxytetracycline, sulfamethoxazole, mebendazole, Potenay, sodium chloride 0.9%, and Mercepton. However, five days after starting the treatment, the bird died. Upon necropsy, prominence of the keel, pieces of undigested food in the oral cavity and proventriculus, intestinal gas, and thickened and turbid air sacs were found. The microbiological analysis of air sacs identified Escherichia coli, Klebsiella pneumoniae, and Enterobacter aerogenes. Histopathological examination showed heterophilic bacterial airsacculitis.

Antimicrobial Susceptibility of Commensal E. coli Isolated from Wild Birds in Umbria (Central Italy)

The role of wildlife, including birds, in antimicrobial resistance is nowadays a speculative topic for the scientific community as they could be spreaders/sources of antimicrobial resistance genes. In this respect, we aimed to investigate the antimicrobial susceptibility of 100 commensal Escherichia coli strains, isolated from wild birds from an Umbrian rescue centre and admitted to the Veterinary Teaching Hospital of Perugia (Central Italy) mainly for traumatic injuries. The possible presence of Salmonella spp. and ESBL-producing E. coli was also estimated. The highest prevalence of resistance was observed for ampicillin (85%) and amoxicillin/clavulanic acid (47%), probably due to their extensive use in human and veterinary medicine. Seventeen out of the one hundred E. coli isolates (17%) displayed a multidrug-resistance profile, including the beta-lactam category, with the most common resistance patterns to three or four classes of antibiotics. Resistance to ciprofloxacin, cefotaxime and ceftazidime exhibited values of 18%, 17% and 15%, respectively. Eight out of the hundred E. coli isolates (8%) were ESBL and seven showed multidrug resistance profiles. Salmonella spp. was not isolated. Resistance to third-generation cephalosporins, also detected in long-distance migratory birds, suggests the need for monitoring studies to define the role of wild birds in antimicrobial resistance circuits.

Antibiotic Resistance and Virulence Profiles of Escherichia coli Strains Isolated from Wild Birds in Poland

Wild animals are increasingly reported as carriers of antibiotic-resistant and pathogenic bacteria including Enterobacteriaceae. However, the role of free-living birds as reservoirs for potentially dangerous microbes is not yet thoroughly understood. In our work, we examined Escherichia coli strains from wild birds in Poland in relation to their antimicrobial agents susceptibility, virulence and phylogenetic affiliation. Identification of E. coli was performed using MALDI-TOF mass spectrometry. The antibiotic susceptibility of the isolates was determined by the broth microdilution method, and resistance and virulence genes were detected by PCR. E. coli bacteria were isolated from 32 of 34 samples. The strains were most often classified into phylogenetic groups B1 (50%) and A (25%). Resistance to tetracycline (50%), ciprofloxacin (46.8%), gentamicin (34.3%) and ampicillin (28.1%) was most frequently reported, and as many as 31.2% of E. coli isolates exhibited a multidrug resistance phenotype. Among resistance genes, sul2 (31.2% of isolates) and blaTEM (28.1%) were identified most frequently, while irp-2 (31.2%) and ompT (28.1%) were the most common virulence-associated genes. Five strains were included in the APEC group. The study indicates that wild birds can be carriers of potentially dangerous E. coli strains and vectors for the spread of resistant bacteria and resistance determinants in the environment.

High prevalence of a gene cluster conferring resistance to streptomycin, sulfonamide, and tetracycline in Escherichia coli isolated from indigenous wild birds

A total of 116 Escherichia coli isolates from cecal contents of 81 indigenous wild birds in Korea were tested for antimicrobial susceptibility. Seventy-one isolates from sparrows (Passer montanus) and one isolate from doves (Columba livia) were resistant to three antimicrobials, including streptomycin, sulfonamide, and tetracycline (SSuT). PCR and subsequent sequence analysis revealed the SSuT gene cluster region (approximately 13 kb) harboring genes encoding resistance to streptomycin (strA and strB), sulfonamide (sul2), and tetracycline (tetB, tetC, tetD, and tetR). In particular, tetracycline resistance genes were located on the transposon Tn10-like element. The SSuT element-harboring E. coli can be an important source of the transmission of antimicrobial resistance to other pathogenic bacteria. Therefore, strict sanitary measures in human and animal environments are necessary to prevent the spread of resistant bacteria through fecal residues of wild birds.

Generalizability and comparability of prevalence estimates in the wild bird literature: methodological and epidemiological considerations

Wild birds have been the focus of a great deal of research investigating the epidemiology of zoonotic bacteria and antimicrobial resistance in the environment. While enteric pathogens (e.g. Campylobacter, Salmonella, and E. coli O157:H7) and antimicrobial resistant bacteria of public health importance have been isolated from a wide variety of wild bird species, there is a considerable variation in the measured prevalence of a given microorganism from different studies. This variation may often reflect differences in certain ecological and biological factors such as feeding habits and immune status. Variation in prevalence estimates may also reflect differences in sample collection and processing methods, along with a host of epidemiological inputs related to overall study design. Because the generalizability and comparability of prevalence estimates in the wild bird literature are constrained by their methodological and epidemiological underpinnings, understanding them is crucial to the accurate interpretation of prevalence estimates. The main purpose of this review is to examine methodological and epidemiological inputs to prevalence estimates in the wild bird literature that have a major bearing on their generalizability and comparability. The inputs examined here include sample type, microbiological methods, study design, bias, sample size, definitions of prevalence outcomes and parameters, and control of clustering. The issues raised in this review suggest, among other things, that future prevalence studies of wild birds should avoid opportunistic sampling when possible, as this places significant limitations on the generalizability of prevalence data.

First Report of KPC-2 and KPC-3-Producing Enterobacteriaceae in Wild Birds in Africa

The increased incidence of antibiotic-resistant Enterobacteriaceae is a public health problem worldwide. The aim of this study was to analyze the potential role of wild birds, given their capacity of migrating over long distances, in the spreading of carbapenemase, extended-spectrum β-lactamase (ESBL), and acquired-AmpC beta-lactamase-producing Enterobacteriaceae in the environment. Fecal and pellet samples were recovered from 150 wild birds in seven Tunisian regions and were inoculated in MacConkey-agar plates for Enterobacteriaceae recovery (one isolate/animal). Ninety-nine isolates were obtained and acquired resistance mechanisms were characterized in the five detected imipenem-resistant and/or cefotaxime-resistant isolates, by PCR and sequencing. The following ESBL, carbapenemase, and acquired-AmpC beta-lactamase genes were detected: bla_CTX-M-15 (two Escherichia fergusonii and one Klebsiella oxytoca isolates), bla_KPC-2 (one K. oxytoca), bla_KPC-3 (one E. fergusonii), bla_ACT-36, and bla_ACC-2 (two K. oxytoca, four E. fergusonii, and two E. coli). The IncFIIs, IncF, IncFIB, IncK, IncP, and IncX replicons were detected among these beta-lactamase Enterobacteriaceae producers. The bla_KPC-2, tetA, sul3, qnrB, and cmlA determinants were co-transferred by conjugation from K. oxytoca strain to E. coli J153, in association with IncK and IncF replicons. Our results support the implication of wild birds as a biological vector for carbapenemase, ESBL, and acquired-AmpC-producing Enterobacteriaceae.

Microbiological diagnosis and antimicrobial sensitivity profiles in diseased free-living raptors

Free-living raptors (birds of prey) can act as reservoirs of potentially zoonotic agents, but they also can be affected by microorganisms as target hosts. In this retrospective study, microbiological results (n = 663) and antibiotic sensitivity profiles (n = 108) of bacterial isolates were analysed from diseased free-living raptors. Sixty-nine percent of cases (n = 457) yielded bacteria: 58% were in pure culture and 42% were of different species. Remarkably, samples from necropsies (47%) had higher percentage of pure isolations than those obtained from clinical (31%) samples (P < 0.001). Among bacterial isolates, Escherichia coli was the most common agent (35%), principally recovered from necropsied birds with clinical signs of septicaemia or respiratory disorders. Pseudomonas aeruginosa (7%) was isolated from birds with systemic infection and from oral lesions, especially in nocturnal raptors (P < 0.001). Staphylococcus spp. (5%), mainly Staphylococcus aureus, was found to be the most prevalent cause of pododermatitis (35%) and Staphylococcus hyicus was isolated from conjunctivitis (18.2%). Interestingly, 8% of samples with lesions compatible with avian tuberculosis were positive to the Mycobacterium avium complex. The most frequent fungi associated with pneumonic lesions and ingluvitis were Aspergillus spp. and Candida spp., respectively. More than 50% of the 108 isolates (34 different bacterial spp.) demonstrated resistance to clindamycin, ampicillin, tetracycline, cefuroxime, enrofloxacin and trimethoprim/sulphamethoxazole. Among the E. coli strains, 71% (27/38) presented a multidrug-resistance pattern to >3 antimicrobials. Detection in wildlife of antimicrobial-resistant pathogens that might be significant at the animal-human-ecosystem interface is of great relevance under the 'One Health' approach.